A servomotor is designed to generate a precise movement of a mechanical component, for example an industrial valve, according to an external command. A servomotor is thus a motorized system capable of reaching predetermined positions, then maintaining them. The position is, in the case of a rotary servomotor, a corner position, and, in the case of a linear servomotor, a distance position. The start-up and preservation of the predetermined position are controlled by the external control.
FIG. 1 diagrammatically illustrates a servomotor 1 of the prior art. The servomotor 1 traditionally comprises a motor unit 2 suitable for generating a movement of a mechanical component, a unit 3 for detecting the position of the mechanical component, and a unit 4 for manually controlling the mechanical component. The motor unit 2 and the unit 3 for detecting the position are adjacent to the manual control unit 4.
The position-detecting unit 3 of the mechanical component, for example, comprises a system 5 for detecting the end of travel, for measuring the distance traveled by the mechanical component, and indicating whether the final position of the mechanical component has been reached. The system 5 makes it possible to measure the torque applied to the mechanical component. The position-detecting unit 3 of the mechanical component can comprise a stress limiter 6 for detecting the torque applied.
The manual control unit 4 is actuated by an actuating means 7, typically a flywheel 7, making it possible to manually control the mechanical component, via a reduction gear of the manual control unit 4. The manual control can in particular be activated during commissioning of the servomotor 1 or in case of breakdown, for example in the event the electrical power of the servomotor 1 is cut.
In this type of servomotor, the manual control unit 4 is positioned inside an enclosure 8, with the exception of the flywheel 7, situated outside the enclosure 8. The enclosure 8 also includes the other components of the servomotor 1, such as the motor unit 2, the position-detecting unit 3, and the manual control unit 4. The enclosure 8 also comprises two cable inlets 9, one cable inlet 9 intended to receive an electrical power cable of the motor unit 2, making it possible to control the motor unit 2 using an external control system, and a cable inlet 9 intended to receive a data transfer cable making it possible to transfer data to the control system relative in particular to the position of the mechanical component. The cable inlets 9 are generally made using a cable gland.
During an intervention on a servomotor, it may be necessary to quickly access the different parts of the servomotor. This is in particular the case during interventions in nuclear power plants, because it is very risky and very expensive to prolong the intervention.
The servomotor illustrated in FIG. 1 does not allow a quick intervention. Indeed, placing the servomotor is a heavy operation, because it is necessary to separate the servomotor unit from the mechanical component actuated by the servomotor. Moreover, the access to the different parts of the servomotor inside the enclosure is particularly complex. Furthermore, once the servomotor is placed, it is no longer possible to use the manual control that is part of the servomotor.
The invention aims to resolve these drawbacks.